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The present invention relates generally to automated systems for traffic violation enforcement, and more specifically to a system employing one or more image capturing devices to predict and record red light violations.
As it is generally known, traffic lights are commonly used to control automobile traffic travelling through road intersections. Typical traffic lights operate using at least red and green light phases, with traffic required to stop when the light is red, and permitted to pass through the intersection when the light is green. A yellow light phase may further be used to indicate that the light will change to red shortly. Driving through a red light without justification may be a citationable traffic offense, referred to herein as a xe2x80x9cred-light violation.xe2x80x9d
Monitoring of traffic intersections for red-light violations has historically been done in-person by one or more law enforcement officers. However, the proliferation of intersections, combined with budget pressures and other resource limitations, have caused police departments to employ automated tools for intersection monitoring. Some existing automated systems have used fixed-position cameras to generate still images of vehicles in response to detection of a violation. Such systems suffer from significant drawbacks due to the poor environment many intersections provide for still photography. Specifically, improper lighting resulting from solar glare, reflections, and shadows may cause photographs taken by such existing systems to be of poor quality and, therefore, ineffective for identifying the operator or the license plate number of a violating vehicle. In addition, systems using fixed position cameras further suffer from problems of driver and/or vehicle identification resulting from occlusion of the violating vehicle by other vehicles. Moreover, the amount of information provided by existing systems regarding the context and/or circumstances surrounding an alleged violation is often insufficient for effective violation enforcement.
For these reasons it would be desirable to have an automated traffic light violation recording system which captures greater amounts of useful image data regarding an alleged red light violation than previous systems. The system should capture sufficient image data regarding the violating vehicle, so vehicle license plate, and/or operator identity can be extracted. The system should be capable of capturing images of multiple violations occurring in close temporal proximity and/or simultaneously, while also recording context information regarding events surrounding the violations. The system should provide sufficient image data for later review such that problems of lighting and/or vehicle occlusion can be avoided or overcome. It would further be desirable for the system to be applicable to intersections in general, and not limited to monitoring of automobile intersections. Providing the capability to similarly monitor and/or record events occurring at railroad crossings, border check points, toll booths, pedestrian crossings and parking facilities would specifically be desirable.
A system and a method for traffic light violation prediction and recording are disclosed, including at least one violation prediction image capturing device, such as a video camera, which provides image data to the system. The image data is processed to generate the locations of a number of vehicles approaching an intersection. The identities and locations of these target vehicles are passed to a violation prediction unit. The violation prediction unit generates violation probability scores for one or more of the vehicles, based on attributes of those vehicles, such as current position, speed and acceleration. The violation prediction unit is further coupled to the traffic light controller itself, and therefore bases its calculation of violation probabilities in part on a detected current light phase, as well as a time remaining and/or elapsed in the current light phase.
The violation probability scores are passed to a violation recording unit, which allocates violation recording resources used to record images of a vehicle or vehicles associated with relatively high violation probability scores. The violation recording unit determines a relatively optimal resource allocation schedule which permits recording of a maximum number of high probability predicted violations. The specific violation recording resources used to record a violation may include, for example, one or more image capturing devices used to capture 1) front and/or rear views of the vehicle in order to extract license plate information, 2) the traffic light as seen by the operator entering the intersection, 3) the vehicle crossing the relevant stop line, 4) an image of the operator, and/or 5) context information showing traffic activity around the violation at the time of the violation. If sufficient resources cannot be allocated to record all predicted violations within a given time period, the violation recording unit may ignore some number of predicted violations having relatively low probability scores.
In an illustrative embodiment, the violation recording resources include a number of violation recorders. A violation recorder may, for example, include digitizing hardware, together with associated control software such as one or more software agents. The violation recorders produce a number of digital data files (xe2x80x9crecorder filesxe2x80x9d) storing image data in a memory, such as digitized video frames, showing multiple views of the violation as it occurred. These recorder files may then be sent, together with associated information regarding the violation or violations, to a server system located remotely from the intersection being monitored, for subsequent review and generation of any citation or citations they show.
Thus there is disclosed an automated traffic light violation system which captures image data regarding an alleged violation or violations, such that images of the vehicle and/or operator may be extracted for identification purposes. The disclosed system is capable of capturing pictures regarding multiple violations occurring within close temporal proximity and/or simultaneously, and also capturing context information regarding events surrounding the violations. The system advantageously provides sufficient image data for later review such that problems of lighting and/or vehicle occlusion may be overcome or avoided. The disclosed system is further applicable to intersections in general, and not limited to monitoring of automobile intersections. Specifically, the disclosed system provides the capability to similarly monitor and record events occurring at railroad crossings, border check points, toll booths, pedestrian crossings and parking facilities. Moreover, the disclosed system may be employed to perform traffic signal control in general and to detect speed limit violations.